1. Field of the Invention
The present invention relates generally to a steering lock system for an automotive vehicle, and more specifically, to an automotive steering lock system incorporating a portable radio signal transmitter which produces a self-identifying radio code signal, wherein a steering wheel can be unlocked only when the transmitter self-identifying code matches a preset reference code so as to enhance safety against theft or unexpected starting of an automotive engine.
2. Description of the Background Art
Various types of an automotive steering lock system have been proposed for locking and unlocking a steering wheel.
In one type of the steering lock system, a control rod is arranged in parallel to an ignition key cylinder. The control rod is movable between a first position where the ignition key cylinder is prevented from shifting between a steering locking position and a steering unlocking position and a second position where the ignition key cylinder is allowed to shift between the steering locking and unlocking positions.
Specifically, a stopper member is fixed onto an external surface of the ignition key cylinder, and an annular guide member is also fixed on the external surface of the ignition key cylinder. The annular guide member has a recessed portion corresponding to a position of the stopper member. The recessed portion extends axially away from the stopper member. The control rod has an engageable end portion which is engageable with the stopper member to prevent rotation of the ignition key cylinder when the engageable end portion is located out of the recessed portion, while such a engagement is not established when the engageable end portion is located within the recessed portion. The recessed portion is located to allow the engageable end portion to move into the recessed portion by manual operation of the control rod when the ignition key cylinder is in its LOCK and OFF positions, but to prevent the engageable end portion from moving into the recessed portion when the ignition switch is in its positions other than the LOCK and OFF positions, i.e. the engageable end portion is guided by a portion of the annular guide member other than the recessed portion. The steering wheel is locked when the ignition key cylinder is in the LOCK position and unlocked when the ignition key cylinder is in the OFF position and the other positions, such as, ACC, ON and START positions.
When the ignition key cylinder is rotated from the other positions to the OFF position, since the engageable end portion of the control rod has been guided by the portion of the annular guide member other than the recessed portion, the engageable end portion is engageable with the stopper member so that shifting of the ignition key cylinder from the OFF position to the LOCK position is prohibited. Accordingly, by the manual depressing operation of the control rod to move the engageable end portion into the recessed portion, the engagement between the engageable end portion and the stopper member is released to allow the ignition key cylinder to shift to the LOCK position so as to lock the steering wheel. On the other hand, when shifting the ignition key cylinder to the OFF position from the LOCK position, since the engageable end portion of the control rod is located within the recessed portion, the ignition key cylinder is allowed to shift to the OFF position to unlock the steering wheel only by rotating an ignition key.
Accordingly, if the ignition key is left in the vehicle, even a mere child can easily unlock the steering wheel to start the automotive engine. This is undesirable in view of the safety.